Dental face bow and method of using same

ABSTRACT

A dental facebow includes a U-shaped frame which carries on its cross-piece a rearwardly projecting bite fork for angular, lateral, and longitudinal adjustments. A fixed stylus is resettably located on one frame arm and an axially adjustable second stylus is carried by the other frame arm. The facebow is used with an articulator having opposite intercondylar adjustments provided with intercondylar setting indicia, and the second stylus carries spacing indicia of twice the scale of the intercondylar setting indicia. In adapting the facebow to a particular articulator the facebow and articulator are adjusted to the same setting indicia and the facebow is brought into engagement with the articulator and the first stylus is reset to effect mating engagement between the articulator and facebow.

l [75] Inventor:

United States Patent Granger 1 1 DENTAL FACE BOW AND METHOD OF USING SAME Ernest R. Granger, Pelham, NY.

[731 Assignees: Richard R. Granger; Robert K.

Granger, both of Pelham Manor, NY.

[22] Filed: July 30, 1973 [21] Appl. No.: 384,077

[451 Feb. 18,1975

Primary Examiner-Louis G. Mancene Assistant Examiner l. Q. Lever Attorney, Agent, 0r Firm-William R. Liberman, Esq.

[57] ABSTRACT A dental facebow includes a U-shaped frame which carries on its cross-piece a rearwardly projecting bite fork for angular, lateral, and longitudinal adjustments. A fixed stylus is resettably located on one frame arm and an axially adjustable second stylus is carried by the other frame arm. The facebow is used with an articulator having opposite intercondylar adjustments provided with intercondylar setting indicia, and the second stylus carries spacing indicia of twice the scale of the intercondylar setting indicia. In adapting the facebow to a particular articulator the facebow and articulator are adjusted to the same setting indicia and the facebow is brought into engagement with the articulator and the first stylus is reset to effect mating engagement between the articulator and facebow.

5 Claims, 4 Drawing Figures DENTAL FACE BOW AND METHOD OF USING SAME BACKGROUND OF THE INVENTION The present invention relates generally to improvements in dental implements and methods and it relates particularly to an improved dental facebow and a method of using the same.

A dental facebow is a device which is used to transfer casts of a mouth from the patient to a dental articulator. The human mouth and skull are never symmetrical. The purpose of the facebow is to mount the casts on the articulator with the same asymmetry as the skull. The conventional facebows are copies of the original Snow facebow developed about seventy-five years ago. It consists of a U-shaped frame which fits around the face. It is held in place by a clamp attached to a bite fork which is held between the teeth, or attached to a bite rim. At each end of the bow is a sliding adjustable stylus, which is positioned outside of each temporomandibular joint. The bow is clamped on the bite fork and the styli adjusted to contact the skin on each side outside of the joint. In use, the styli must be adjusted to be equidistant from the skin on each side. For this purpose each stylus is ruled in one millimeter lines, and the clamp on the bow must then be locked in this position. It is very difficult to maintain exactly equal contact with the skin and lock the bow in this position.

To transfer this relation to the articulator after the bow has been removed from the face, the styli must then be readjusted to fit the articulator. To do this, the styli must then be readjusted, again equidistant, to fit the size of the particular articulator being used. The intercondylar marking on an artiuclator represents the distance between the center of rotation of the condyles on the articulator, wheras the millimeter markings on the styli register the skin distance of the outside of the skull. Since the centers of rotation are located inside the skull, the millimeter markings on the styli cannot be used to adjust the intercondylar distances of the articulator. During all these procedures, the markings of the styli on each side must be kept identical. In use, the facebow mounting usually requires the efforts of two people working together; one to hold the facebow, and another to lock it without moving the styli.

SUMMARY OF THE INVENTION It is a principal object of the present invention to provide an improved dental device and an improved method of employing same.

Another object of the present invention is to provide an improved dental facebow and an improved method of employing the same.

Still another object of the present invention is to provide a device and method of the above nature characterized by ease, reliability, and simplicity of application, and great versatility and adaptability.

The above and other objects of the present invention will become apparent from a reading of the following description taken in conjunction with the accompanying drawing.

The facebow in accordance with the present invention has one fixed locked stylus and one sliding stylus. The sliding stylus is marked in lines which are two units or millimeters apart, but are marked as single units or millimeters would be. For example the markings from say 45 to 50 are actually 10 millimeters apart. These numbers do not represent the distance between the points of the stylus, or skin distances as on a conventional facebow. They are positioned on the moveable stylus, so that the number which is read from the stylus is the intercondylar setting of the particular articulator, on both sides, at the outside width of the articulator and skin distance of the patient.

The improved facebow functions not only to transfer the asymmetry to the articulator, but to act as a computer and make this transfer automatically at the correct intercondylar distance. On all dental articulators the intercondylar settings are marked in one millimeter increments to measure the distance between the cen ters of rotation of the condyle, not the width of the articulator, nor skin width of the patient. The improved facebow thus serves a dual purpose with one setting and provides a much more accurate, simpler, quicker and easier procedure, and is highly reliable, versatile and adaptable.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is atop plan view of a facebow embodying the present invention;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view; and

FIG. 4 is a rear elevational view thereof, partially in section.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now the the drawing which illustrates a preferred embodiment of the present invention, reference numeral 10 generally designates the improved facebow which is employed, by way of example, with a conventional articulator having a millimeter indexed type of intercondylarsetting. Face bow 10 comprises a U-shaped bow frame 11 formed of a light weight material such as an aluminum alloy, and includes a straight transverse cross-piece l2 and parallel rearwardly directed side arms 13 and 14. The dimensions of frame 11 approximately corresponds to those of the conventional facebow.

Transversely mounted on and fixed to the free end of side arm 14 is a short, upwardly projecting round post 16 having a transverse main bore proximate its upper end. A stationary stylus 17 engages the bore in post 16. The stylus 17 is directed transversely inwardly and is of cylindrical configuration terminating at its inner end in a roundedconical tip 18.

A second rounded post 19 is mounted on and is directed vertically upwardly from the free end of arm 13, aligned with post 16, and is provided with a main bore in axial alignment with the main bore in post 16, and a threaded tapped vertical bore transversely communieating with the main bore in said post 19. Axially slidably engaging the main bore in post 19 is a longitudinally adjustable elongated stylus 20 of cylindrical configuration which is inwardly directed and in coaxial alignment with stationary stylus l7, and terminates at its inner end in a rounded conical tip 21.

A longitudinal groove 22 is formed in the top face of stylus 20 and extends for a major part of the length thereof. A thumb screw 23 engages the threaded tapped bore in post 19, and extends upwardly and slidably engages groove 22 to permit the alternate locking of stylus 20 in an adjusted position and the release thereof for axial readjustment. Formed in the face of stylus 20 are regularly longitudinally spaced peripherally extending line marks 24, the mark spacing being twice scale; specifically, the distance between successive marks 24 is 2 millimeters. The front face 26 of stylus 20 is flatted and has impressed therin similar numbers 27 which enumerate the marks 24 and as the marks'are at twice scale and are suitably correlated with anassociated articulator, as will be hereinafter set forth.

Adjustably mounted in cross-piece 12 of the bow frame is a bite fork 28 which includes a tubular shank 29 assymmetrically rigidly supporting at its rear free end a curved bite piece 30 of conventional configuration and construction. The front section of fork shank 29 is engaged by an adjustable clamp assembly 32 which is adjustable along the cross-piece l2. Clamp assembly 32 includes an upper U-shaped clamp member 33, having upper and lower parallel clamp arms 34 and 36 embracing the frame cross-piece l2, and provided with vertically coaxially aligned bores, the bore in upper clamp arm 34 being tapped. Underlying upper clamp 33 is a lower clamp member 37 which includes upper. and lower clamp arms 38 and 39 which embrace fork shank 29, the upper clamp arm 38 underlying clamp arm 36. and spaced therefrom by a serrated washer. Bores are formed in arms 38 and 39 in vertical axial alignment with those in clamp arms 34 and 36, and a clamp tightening screw 40 registers with these bores and engages the tapped bore in clamp arm 34. Tightening screw 40 terminates at its bottom in a head 41 confronting the underface of clamp arm 39 and having a diametrically extending finger rod 42.

Another clamp arm assembly 43 similar to clamp assembly 32 but tightenable by an Allen screw engages the cross-piece 12 and functions to support other accessories such as a handle or the like.

To use facebow 10, it is clamped in ths usual fashion to a bite fork 28,-with th'efixed stylus tip 18in contact with the skin over the temporomandibular joint. The released movable stylus 20 is slid to make contact with the skin on the other side, and the number 27 and mark 24 on the stylus is recorded. To transfer this data to the articulator, the intercondylar distance of both sides of the articulator is set to the measurement read from stylus 20, and facebow l transferred to the articulator at the same setting as it had on the patient. This is the reason for the two millimeter spacing of the lines on the moveable stylus.

However, on all dental articulators the distance from the center of rotation of the condyles to the outside dimension of the horizontal axis is different. Consequently, the markings on the stylus must represent the distance between the outside dimension of the articulator minus the distance from the outside to the centers of rotation as marked on the intercondylar setting of the articulator. For example, if on a particular articulator the distance on each side from the center of rotation to the outside dimension is mm then the numbers on the stylus must correspond to the distance between the points of the styli, minus the 30mm added width of the articulator. Then when the number is read distance between the intercondylar settings of the articulator.

Facebow 10 can be readily adapted to the various widths of different articulators by this method. The unmarked stylus is held in place by a screw. The articulator is adjusted to any given intercondylar setting, such as say 50 millimeters. The moveable stylus is set and locked at the number 50. It is placed on the articulator, and the unmarked stylus moved in to contact the other side of the articulator. It is locked in this position. Now

the number read from the-moveable stylus is the intercondylar setting-of the articulator. Once this adjustment has been made for use on any particular make of articulator, it remains fixed for all future mountings when used with this articulator. It can readily be changed for use on any other articulator.

Thus it can be seen that this facebow performs dual function. It not only transfers the cast to the articulator at the correct asymmetry, but also computes the correct intercondylar setting of the articulator and accomplishes the transfer at the correct intercondylar width.

While there has been described and illustrated a pre ferred embodiment of the present invention, it is apparent that numerous alterations, omissions and additions may be made without departing from the spirit thereof.

I claim: v

I. In combination with a dental articulator having intercondylar markings separated by uniformfirst increments and numbers indicative of said markings, a dental facebow comprising a U-shaped frame including a cross-piece and a pair of rearwardly directed side arms, a stationary first transversely inwardly directed stylus mounted proximate the free end of one of said side arms, an axially movable second transversely inwardly directed stylus mounted proximate the free endof the other side arm and having longitudinally spaced markings separated by uniform second increments of twice the length of said first increments and carrying numbers indicative of said markings thereon and which correspond to the intercondylar numbers on said articulator, the styli being axially aligned,,a bite form including a rearwardly disposed bite section and a forwardly directed shank, and a universally adjustable coupling slidably adjustable along said cross-piece and axially adjustably engaging said form shank.

2. The dental facebow of claim 1 including means for resetting said stationary first stylus to a locked position correlating the numbered markings on said axially adjustable second stylus with the respective numbered markings on said articulator.

3. The dental facebow of claim 1 including fingeractuated means for releasably locking said movable second stylus in adjusted positions.

4. The dental facebow of claim 1 including means for releasably locking said coupling member and said bite fork in preadjusted positions.

5. The method of employing the facebow of claim 1 comprising the steps of adjusting said movable second stylus and the intercondylar members of said articulator to the same number designations and applying said facebow to said articulator and resetting said first stylus to effect the mating engagement between said facebow and said articulator.

i i i i 

1. In combination with a dental articulator having intercondylar markings separated by uniform first increments and numbers indicative of said markings, a dental facebow comprising a Ushaped frame including a cross-piece and a pair of rearwardly directed side arms, a stationary first transversely inwardly directed stylus mounted proximate the free end of one of said side arms, an axially movable second transversely inwardly directed stylus mounted proximate the free end of the other side arm and having longitudinally spaced markings separated by uniform second increments of twice the length of said first increments and carrying numbers indicative of said markings thereon and which correspond to the intercondylar numbers on said articulator, the styli being axially aligned, a bite form including a rearwardly disposed bite section and a forwardly directed shank, and a universally adjustable coupling slidably adjustable along said cross-piece and axially adjustably engaging said form shank.
 2. The dental facebow of claim 1 including means for resetting said stationary first stylus to a locked position correlating the numbered markings on said axially adjustable second stylus with the respective numbered markings on said articulator.
 3. The dental facebow of claim 1 including fingeractuated means for releasably locking said movable second stylus in adjusted positions.
 4. The dental facebow of claim 1 including means for releasably locking said coupling member and said bite fork in preadjusted positions.
 5. The method of employing the facebow of claim 1 comprising the steps of adjusting said movable second stylus and the intercondylar members of said articulator to the same number designations and applying said facebow to said articulator and resetting said first stylus to effect the mating engagement between said facebow and said articulator. 